In many cases, molded products made of a polyolefin such as polyethylene or polypropylene are used in the state that the surface is painted with a paint in order to improve the beautification property, endurance and other properties. However, polyolefin is low in polarity and is poor in adhesiveness to the paint, so as to result in a problem that the painted film is easily peeled.
It is well known that a paint comprising a cyclized product of a conjugated diene polymer such as polyisoprene adheres well to polyolefin (Japanese Patent Application Laid-Open (JP-A) No. 51-12827). In order to improve the adhesiveness further, the use of a modified conjugated diene polymer cyclized product is suggested, which is obtained by adding maleic anhydride to a conjugated diene polymer having a low molecular weight and containing 70% or more of cis-1,4 bonds, then conducting cyclization-reaction (JP-A No. 57-145103).
Although the use of a conjugated diene polymer cyclized product as described above makes it possible to yield a paint whose adhesiveness to a polyolefin molded product is somewhat good, the degree of the improvement is insufficient.